1. Field of the Disclosure
The present invention relates to a backlight unit in which an LED driving voltage is stabilized, and a method for driving the same.
2. Discussion of the Related Art
In general, a liquid crystal display device displays a picture by controlling light transmissivity of liquid crystals having dielectric anisotropy by using an electric field. To do this, the liquid crystal display device is provided with a liquid crystal panel having a liquid crystal cell matrix, a driving circuit for driving the liquid crystal panel, and a backlight unit for directing a light to the liquid crystal panel.
Recently, as the backlight unit, an LED backlight unit which uses a light emitting diode LED as a light source is spot lighted, which has advantages of high brightness and low power consumption in comparison to the present lamp.
A related art LED backlight unit is provided with a plurality of LED arrays, a voltage generating unit for generating a driving voltage to drive the plurality of LED arrays, a feedback circuit for feeding the driving voltage back to the voltage generating unit for stabilizing the driving voltage, and a dimming control unit for controlling a current to the LED arrays in response to a dimming signal from a timing controller to control brightness of the light.
In the meantime, the dimming signal is a pulse width modulation signal having a predetermined duty value. However, there has been a problem in that a switching delay of the feedback circuit causes a ripple in which the driving voltage drops slightly at the time the dimming signal rises from a low state to a high state. Such a ripple of the driving voltage affects the LED driving current, to cause defect of the brightness.